Metal extrusion press



April 6, 1954 A. LATIN METAL ExTRusIoN PRESS 5 shetssheet 1 Filed July2, 1951 Inventor Aub/"ey L atm By i M Attorneys April 6, 1954 A. LAT,2,674,373

METAL EXTRUSION PRESS Filed July 2, 1951 5 Sheets-Sheet 2 F G. 2. ,2 l[f4 il 40 /f/ A ttorney April 6, 1954 A LATlN 2,674,373

METAL ExTRUsIoN PRESS Filed July 2, 1951 5 Sheets-Sheet 3 Inventoru/brej/ Lai/h ttornys n Inventor l Aub/"ey Lczzm Attorneyg 5Sheets-Sheet 4 A. LATIN METAL EXTRUSION PRESS April s, 1954 Filed July2, 1951 (O (D l Filed July 2 1951 April 6, 1954 A. LATlN 2,674,373 METALExTRUsIoN PRESS 5 Sheets-Sheet 5 f Inventor ttorney s Patented pr. 6,"1954 METAL EXTRUSION PRESS Aubrey Latin, London, ish Insulated GallenEngland, assigner to Britders Cables Limited, London, England, a Britishcompany Application J uly 2, 1951, Serial No. 234,765

Claims priority, application Great Britain July 5, 1950 7 Claims.

This invention relates to extrusion presses for metals, for instance,aluminium and aluminium alloys, in which the metal to be extruded is putinto the extrusion cylinder or container in the form or" a heated billetor billets shaped to iit the cylinder, which may, or may not, contain acentral mandrel. A ram working from the rear end of the container forcesout the metal through a die or between inner and outer dies in the frontend of the container.

An object of the invention is to secure good union between the metal ofsuccessive billets and thereby permit of extrusion taking place in greatlengths without the formation of defective parts where two billets cometogether and intermingle.

The irregularities of the metal which lead to `the production of defectsare largely found in the outer cylindrical surface of the billet and thedirectly adjacent region, being due both to surface contamination and tolocal temperature diierence, accompanied by other physical diierences.

The flow of metal through the press is also frequently such as -to leadto the collection of what may be termed dead metal near the outer walls,particularly near the front end of the press, and there is alsofrequently an accumulation of defective material at or adjacent to thisregion of dead metal. There is also a tendency for defective material toflow towards the central part of the rear end of the billet. It is anobject of this invention to elTect a removal of some or all of thedefective material and to improve the ow characteristics of the metalbeing extruded.

The invention provides for the diversion of some portion of the billetfrom the outer or some other part of it as discarded metal which doesnot pass -to the die or dies. Ports placed near the extrusion end of theextrusion cylinder or container in the wall thereof provide for thisdiversion, the ports being placed and shaped appropriately to secure thepassage out of the container of the metal to be discarded. The containerwall, at, or adjacent to these ports, may have an inward step to producea part near the extrusion end of smaller cross-section than the mainbody of the container. The ports then are placed just before or at thisstep and may be parallel with the axis of the container or may beinclined outwards.

The diversion ports may be so dimensioned and shaped that relative tothe main course of the metal resistance to outflow is such as to divertthe desired portion of the billet section, for instance, from 5-25%according to the conditions oi the case. Since the pressure required toextrude the metal through these diversion ports may be less than thatrequired for the extrusion of the product itself, it is arranged thatthe rejection of the unwanted metal should take place only at intervals,for instance at the beginning and/or end of the extrusion stroke for itis at the beginning and end of the extrusion stroke that defects arelikely to occur and the maximum benet obtained by the diversion andrejection of the unwanted metal. This is accomplished by provision ofmeans for opening and closing such ports as and when required. Suchmeans may, for example, comprise a movable shutter or shutters which areslidable across the face of the ported wall of the container to closethe ports as and when required, shearing off the rejected metal as theydo so.

The invention will now be more fully described with the aid of theaccompanying diagrammatic drawings wherein- Figure l shows partly inelevation and partly in section an example of an aluminium billet pressof which the extrusion cylinder is provided with diversion ports inaccordance with the invention,

Figure 2 is a fragmental section drawn to a larger scale than Figure 1and showing the diversion ports and their closure means more clearly,

Figure 3 is a section taken in Figure l,

Figure 4 is a fragmental section drawn to a larger scale than Figure 1and showing an example of an extrusion press constructed in accordancewith the invention and suitable for applying an aluminium sheath to acable core,

Figure 5 is a fragmental section on the line V-V of Figure 4,

Figure 6 is a View partly in elevation and partly in longitudinalsection of a further example of a billet press provided with ports inaccordance with the invention, and

Figure 7 is a cross-section taken on the line VII-VII in Figure I6.

A description will rst be given of the press shown in Figures 1-3 of thedrawings. As Will be seen it is a vertical press comprising an extrusioncylinder or container l for receiving a billet 2 which is ejectedthrough a die 3 by means of a ram 4. The press is of the type in whichthe container is mounted on a table 5 secured to the ram 6 of ahydraulic cylinder 'i and the exon the line Ill- III trusion ram 4 isrigidly supported above the container I by a cross-head 8 mounted aboveand secured to the hydraulic cylinder 'I by pillars 9, which in thiscase are four in number. The container I is built up of inner and outerliners I and II housed in an outer shell I2. The shell I2 is secured tothe table 5 by bolts I3 and the outer liner I2 is fitted with tubularelectric heaters I4 by means of which the container may be maintained ata suitable extrusion temperature.

having a throated aperture I8 and an upper part .i

I9 having a central dependent projection 28 of which the lower endenters the throat I8 and co-operates with it to dene an annularextrusion orifice. Around the dependent projection is an invertedannular channel 2| co-operating with the upper end 22 of the throatedaperture in the lower part i1 to form an annular chamber leading to theextrusion orice and into which metal is forced through three feed ports23.

The upper part of the die holder forms a continuation of the liner` I8but its bore is less than that of the liner I6 so as to form a step 24in the wall of the extrusion cylinder or container. In this step, inaccordance with our invention, there is provided a ring of holes 25which extend through the die block, preferably in directions parallel tothe axis of the block, as shown. These holes 25 may be so dimensionedand their number be such that collectively they allow a desiredproportion of the billet, for instance from 5 to 25%, to pass throughthem to carry away the defective meta-l from the peripheral part of thebillet. In such case the bolster I6 holding the die holder in place willbe correspondingly apertured as shown at 26 to allow the ejected metalto escape, the holes 25 in the bolster preferably being of greaterdiameter than the rejection ports 25. I prefer however to make the ports25 larger than is required to divert from 5 to 25 of the billet frombeing extruded through the annular die orice and to a-rrange thatrejection of unwanted metal takes place only at the beginning and/or endof the extrusion stroke by arranging for the bolster i6 to be capable ofa rotary movement sufficient to open and close the diversion ports 25,and. thus to serve as shear blades capable of shearing off the discardedlengths of metal as the bolster moves from its opento its closedposition. Naturally this places a limitation upon the number or size ofthe ports 25 since each must then be spaced circumferentially from theadjoining ports by a distance greater than the port diameter.

As will be seen from Figures 2 and 3 I provide in this particularexample of press ten diversion ports of which the collectivecross-sectional area approximates to 12% of the cross-sectional areaofthe container bore but naturally more holes of smaller diameter may beprovided or fewer holes of somewhat larger diameter. The collective arearequired is not critical when the quantity of rejected metal can becontrolled by varying the time during which the ports are open. Tofacilitate entry of defective meta-l into the ports they are located inan annular channel in the radially outer part of the annular step 24,Between each two neighbouring ports 25 in the channel, the channel depthincreases from a minimum midway between the ports to a maximum at theedges of the ports.

The bolster I6 is given a limited angular movement in its housing in thesurface of the table 5 by means of a worm 21 cut in a shaft 28journalled in the table 5 and carrying a. hand wheel 29. The worm 2lengages a worm wheel segment 30 cut in the periphery of the bolster.Normally this bolster is tightly clamped between the container I and thetable 5 in order to form a satisfactory shutter for the ports 25. It isreleased by means of the ram 3l of a hydraulic cylinder 32 housedbeneath it in the table 5. This ram carries a group of thrust pins 33which freely pass through arcuate slots 34 in the bolster I6 and engagethe underside of the container I. By applying sufficient pressure to theram to cause the bolts I3 to stretch elastically to a slight extent, thebolster IB is temporarily released and is able to be rotated by applyinga power drive to the worm sha-ft 28 or by turning the hand wheel 29.

The tubing extruded through the die 3 passes vertically downwards andround a guide pulley 35 and out through an opening 36 in the wall of thepillar 3'! supporting the table 5.

The press shown in Figures 1 3 is suitable for the production ofcoreless tubing. To enable it to sheath a cable core modifications arenecessary. These are shown in Figures 4 and 5 from which it will be seenthat a mandrel or core tube 4| is provided for leading the core to theinner extrusion die or point 42. The wall of the mandrel may be cavitiedto allow of the circulation of a coolant. The mandrel 4I and the innerdie or point 42, may be supported by the upper part of the die holderor, as shown by a perforated plate or spider 43 interposed between theinner liner I0 and the die holder I5. In place of the solid ram 4, shownin Figure 1, a tubular ram 44 is used for operating on billets ofcorresponding form. Apart from these diiferences the press resemblesthat shown in Figures 1-3, and similar parts have been given the samereference numerals. The passages 45 in the spider 43 are uniformlydistributed around the core tube 4I and the point- 42 and lead to theports 25 and tothe annular forming chamber 46 in the die holder. As willbe seen from Figure 5 the passages 45 and ports 25 are circumferentiallyaligned. This is the preferred arrangement. If they `arefnot so alignedit is desirable to provide an annular channel 41 in the upper face ofthe die holder to lead metal from the passages 45 to the ports 25 whenthe-bolster I6 is set in the rejection position.

In the horizontal aluminium billet press shown in Figures 6 and '7 thecontainer 5I resembles the container I shown in Figures 1 3, in that itcomprises a liner 52 and a stepped die holder 53 housed within lan outerliner 54 which is itself housed in a container vbody 55. In this case,however, the container body, filled with heaters 55a, is mounted in aholder 55h in a known manner which allows for radial expansion of thebody. The holder is supported by beingy threaded on four horizontal tierods 56 connecting the main crosshead 5'I to a hydraulic cylinder 56 inwhich works the ram 59 which operates the movable crosshead 60 whichslides on the tie rods 56 between the collars 6l and 62 and carries theextrusion ram 63. The die 64 and its holder 53 are of the same formaslthose shown in Figures 1-3 and need no further description. They areVheld in place and supported against the thrust of the extrusion ram by abolster 65 which is recessed on its rear face to receive a boss 66 onthe adjacent face of a slidable bolster support cross-head 6l. The head66 forms a trunnion co-axial with the container, on which the bolster isrotatably supported. The bolster 65 and its support are urged towardsthe container body 55 by a slidable centrally apertured wedge 68 whichco-operates with a fixed centrally apertured wedge 69 housed in theadjacent face of the main cross-head 51.

'I'he sliding wedge 6s is tightened and slackened by means of a,hydraulic ram 10 working in a cylinder 1I carried by a bridge 12 whoseends are anchored to the two upper tie rods 56. When the wedge isslaokened the bolster 65 is free to rotate through a limited anglesuiicient to move it from a position in which the ports 12 in the dieholder are closed by the bolster into a position f in which the throughpassages 'i3 in the bolster register with the ports. This movement iseffected by a second ram 14 working in a cylinder 15 on a bracket 'I6 onthe cross-head 6l and carrying at its free end a gudgeon pin 'Il workingin slots I8 in two radially projecting brackets 'I9 on the periphery ofthe bolster 65.

It will be appreciated that a Wedge device of this kind may be used tohold up the bolster I6 of the press shown in Figures 1-3. in which casethe hydraulic ram 3| and thrust pins 33 are dispensed with. It will alsobe understood that rotation of the bolster I6 may be effected by meansof a hydraulic ram in the way described with reference to Figures 6 and7 and that the bolster 65 shown in Figures 6 and 7 may be rotated byworm gear in the manner described with reference to Figures 1-3 insteadof by a hydraulic ram, if required. In the examples of presses shown inthe drawings the bolsters I6 and 65 serve both to hold up the die and asa shutter for closing the outlet ends of the diversion ports but it willbe apparent that these functions may be performed by separate members ifrequired.

It will be seen that in all the examples described there is a step inthe Wall of the cylinder of the container where the liner meets thedieholder and that this stop causes an obstruction to the forwardmovement of the main body and produces an additional working of themetal before it reaches the die. It is believed that additional workingof the metal in this region is advantageous. Naturally, the step alsolimits the stroke of the ram which is of a cross-section suitable forworking in the main part of the cylinder, i. e. that constituted by theinner liner l0 or 52. It will be apparent from Figure 4, that inaddition to the effect due to the step 4l, additional working will becaused to take place by the insertion of the perforated plate or spiderserving to support a. central mandrel and that this plate or spider willfurther limit the stroke of the ram. In some cases it may beadvantageous to obtain working of the metal by inserting a perforatedplate or spider instead of by providing a step in the cylinder wall buta step is preferable as it provides an ideal location for the entrancesto the diversion ports.

It will be apparent that the press shown in Figures 6 and 7 may beadapted for the sheathing of cable cores by replacing the die 64 by anouter die and fitting an oil or water cooled tubular mandrel carrying atubular inner die, e. g. as shown in Figure 4. Naturally the extrusionram and the main hydraulic ram must then be tubular and the latter carrya tubular tail which projects through the tail end of the cylinder 58.

In working in accordance with the improved method I prefer, as I haveindicated, to limit the time during which metal is discarded through thediversion ports and to proceed as follows: After withdrawing the ram ahot billet is inserted and, the diversion ports being closed by therotatable bolster, the ram is advanced and the metal of the billet isforced forward rst filling the ports and then extruding through the dieorifice. Before the extrusion ram completed its stroke it is stopped,leaving about 20% of the billet in the container. The ram is thenwithdrawn, the bolster rotated to open the rejection ports and a freshbillet is inserted in the container and the ram re-inserted and advancedto expel through the ports the tail end part of the rst billet, in whichpart the greater portion of contaminated or defective metal from thefirst billet is to be found, and if required the nose end part of thefresh billet also. The ram is then withdrawn slightly to release thepressure on the metal, the bolster rotated to shear 2 through the rodsof rejected metal and close the ports, after which the ram is advancedonce more to extrude all or the remainder of the metal of the secondbillet except the tail end amounting to about 20%, whereupon the ram iswithdrawn, the bolster rotated to open the ports and a new billetinserted and the cycle repeated. It will be understood that the gure of20% is mentioned by way of example and that it may be found that it isunnecessary to discard such a high proportion of the billet as 20%.

To assist the process of transferring contami-v nated metal to theradially outer part of the cylinder where it can be expelled through theports, the adjoining faces of the ram and the billet and those of oldand new billets are arranged to be of such a form that contact isinitially made in the central part of the two surfaces and the area ofcontact gradually enlarged so that any gas located between the surfacescan escape laterally. This may be done in either of two ways. The frontend of the ram may be made concave as shown for example at 8l in Figure1, in which case the tail end of each billet is made convex with aradius of curvature slightly less than that of the concave surface ofthe ram, as shown at 82. With a ram of this form the residue of metal inthe cylinder will have been shaped by the ram so as to be convex.Accordingly the front end of each new billet should be at or concavewith a larger radius of curvature than that of the residue.Alternatively the front end of the ram may be convex, as shown forexample at 83 in Figure 4. In this case the tail end of each new billethas a radius of curvature greater than that of the face of the ram, andis preferably at but ythe front end should be made convex with a radiusof curvature slightly less than the radius of curvature of the convexface of the ram.

What I claim as my invention is:

1. A billet press for extruding metal, comprising a container forreceiving a billet of extrudable metal, an extrusion ram for forcingsaid metal from said container through an extrusion orifice, ports atthe front end of said container for the escape from said container ofextrudable metal containing defective material, and means for openingand closing said ports as and when required.

2. A billet press for extruding metal, comprising'a container forsreceiving La'billet of extrud able' metal, an extrusion ram for forcing`said metal from said container through an` extrusion orice, ports at thefront end of said container for the escape from said containerofext-rudable metal containing defective material, and a slidableshutter for closing each of saidports, said shutter serving as it closes-the port to shearA oi rejected metalescaping through the port.

3; Abillet press for extruding metal, comprising a container forreceiving a billet of extrudable rmetal, an extrusion ram for forcingsaid metalfromfsaid container through an extrusion orice in the frontend Wall of said container, a ring of ports for the escape ofmetal'containing defective material surrounding the extrusion orice, abolster for supporting the front end Wall of said container, said'bolster having a ring of apertures,. and means for rotating saidbolster about the axis of said container from a position in which itsapertures register with the outlet ends of said ports toa position inwhich it closes the outlet ends of said ports.

4. A billet press as claimed in claim 3, in which a holder for anextrusion die forms at least part of the front end wall of saidcontainer and said ports are located in said die holder.

5. A billet press for extruding metal, comprising. a container forreceiving a billet of eX- trudable metal, an extrusion ram for forcingsaid metal from said container through an extrusion orifice in the frontend wall of said container, a ,ring of ports for the escape of metalcontaining defective material surrounding the extrusion orice, acontainer support, a mult-aperf tured bolster between said container andsaid container support, bolts for clamping said bolster between saidcontainer and said container support, means for stretching said boltselastically to release said bolster from the clamping action of saidbolts, and means for rotating said bolster,

8 when released', about the 'axis of saidcontainer from a position inwhich apertures lin said bolster register with the-outlet ends of saidports tol a position in which it 'closes Vthe outlet ends`r of saidports.

6. A billet press -as speciiied in claimv 5, wherein saidbolt-stretching means comprises'a hydraulic ram-and a plurality ofthrust pins carri`ed on said lram and passing through slotsl in saidbolster.'

7. A billet press for extruding metal, comprising acontainer'forreceiving 'a'billet of vextrudable-metal, an extrusion ram for forcingsaid metal from said container through an extrusion orice` in the frontend wall of said container, a ringof ports for the escape of metalcontaining defective material surrounding the extrusion orice, acontainer support, amulti-apertured bolster between said container andsaid container support, a centrally aperturedr wedge between saidbolster and said container support for holding said bolster against theend Wall of said container, means forV tightening and loosening saidwedge, and means for rotating said bolster, when released bylooseningvsaid Wedge, about the axis of said container from a positionin which apertures in said bolster register with the outlet ends of saidports to a position in which it closes the outlet ends -of said ports.-

References Cited in the file of this patent UNITEDv STATES PATENTSNumber Name Date 327,835 Tatham Oct. 6, 1885 1,720,722 Dean July 16,1929 FOREIGN PATENTS Number Country Date 271,378 Germany Feb. 8,1913570,262 Germany Aug. 4, 1931

